1) Field of the Invention
The field of this invention relates to sample source interface and more particularly to a liquid sample collection device that also can be used as a sample return apparatus.
2) Description of the Prior Art
Drugs are commonly manufactured in the form of pills.
The reason for using pills is that when the drug is swallowed by a human, the drug will be disseminated into the body over a period of time as the pill dissolves. Manufacturers of pills are required by law to determine the precise dissolving characteristics of their pill before it is placed on the market. In order to determine the dissolving characteristics of pills, dissolution test equipment in the form of stations are utilized. Although dissolution test equipment is commonly used in conjunction with drugs designed for human consumption, it is considered to be within the scope of this invention to use it with other animals such as horses, cows, rabbits, cats, dogs, monkeys, and so forth.
Every known form of dissolution test equipment utilizes one or more liquid containing flasks. In each flask is to be placed a solution with that solution essentially duplicating the liquid solution that is contained within the stomach of the human body. A precise quantity of the solution is placed within the flask. The pill is then inserted within the flask with the time of the insertion then noted. A mixing paddle is mounted within the flask with mixing at a precise rate of the liquid contained within the flask then occurring. The mixing procedure is to duplicate the natural turbulence that is created within the stomach of the human. Aliquots or samples are removed from the solution at precise time intervals with these samples then being analyzed to determine the amount of the drug that has been dissolved within the solution in relation to the time the pill has been in solution.
In order to insure that this testing process is accomplished as accurately as possible, such dissolution test equipment in the past has been designed to have a plurality of flasks, such as six or eight. Dissolution testing of the pill is accomplished simultaneously in all six or eight flasks with each flask to receive a pill. The average dissolving rate is then calculated between the flasks. It is important that each flask contains precisely the identical amount of liquid. If the flask contains different volumes, inherently the dissolving rate of a pill within one flask can be significantly changed relative to another flask. Additionally, the temperature of the liquid within each of the flasks is also to be identical. It is also important to achieve the precise turbulence in each of the flasks with it being understood that if a flask encounters a greater amount of turbulence, that flask will typically have a faster dissolving rate. Therefore, it is desirable when removing of samples that such be accomplished with a minimum degree of turbulence. Also, the return of liquid to the liquid source is to be accomplished in a manner minimizing the disruption of the liquid contained within the flask.
In the past, to remove and replace samples and add liquid to a flask, there was mounted two separate tubes in conjunction with the flask. One tube was used to remove liquid and the other was used to add liquid. The disadvantages of such a system was that (1) two separate tubes were required and (2) the return tube supplied liquid to the flask in a manner that was disruptive to the liquid in the flask increasing turbulence in the flask producing inaccurate readings of the dissolution rates of the pill in the flask.